U.S. patent number 6,286,762 [Application Number 09/401,363] was granted by the patent office on 2001-09-11 for method and apparatus to perform a predefined search on data carriers, such as rfid tags.
This patent grant is currently assigned to Intermec IP Corp.. Invention is credited to Daniel B. Bodnar, Andrew E. Reynolds, Christopher A. Wiklof.
United States Patent |
6,286,762 |
Reynolds , et al. |
September 11, 2001 |
Method and apparatus to perform a predefined search on data
carriers, such as RFID tags
Abstract
A data carrier reader is capable of executing a number of
different reading methods. One method performs an inclusive search,
identifying all RFID tags having a characteristic data string that
appears on a list of characteristic data strings, for example,
stored in a buffer. Another method performs and exclusive search,
identifying any RFID tags having a characteristic data string that
does not appear on the list. In each method, the data carrier
reader provides a consistent and intuitive output the user to
identify the successful and unsuccessful operations such as
locating a desired RFID tag on the list or missing from the
list.
Inventors: |
Reynolds; Andrew E. (Bothell,
WA), Wiklof; Christopher A. (Everett, WA), Bodnar; Daniel
B. (Duvall, WA) |
Assignee: |
Intermec IP Corp. (Beverly
Hills, CA)
|
Family
ID: |
23587443 |
Appl.
No.: |
09/401,363 |
Filed: |
September 21, 1999 |
Current U.S.
Class: |
235/472.01;
235/472.02 |
Current CPC
Class: |
G06K
7/0008 (20130101); G06K 7/10039 (20130101); G06K
7/10386 (20130101) |
Current International
Class: |
G06K
7/00 (20060101); G06K 007/10 () |
Field of
Search: |
;235/472.01,472.02 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Specifying and Installing Amtech Products, Dallas, Texas, Jun.
6-10, 1988, "The AUX-2 Serial Port", pp. 1, 6, and 7. .
Command codes for the Amtech Model AI-1200 Reader, Versions 2.1,
2.2 and 2.30, Oct. 11, 1988, pp. 1 and 33. .
Amtech Corporation Product Catalog 1194, Readers, 1994, pp. 1-10,
1-11, 1-20, and 1-21..
|
Primary Examiner: Pitts; Harold I.
Attorney, Agent or Firm: Seed IP Law Group PLLC
Claims
We claim:
1. A method of automatically searching RFID tags, comprising:
storing a number of characteristic data strings in a buffer;
reading a respective characteristic data string from each of a
number of RFID tags; and
identifying any of the RFID tags that have the respective
characteristic data strings that correspond to the characteristic
data strings stored in the buffer after reading the respective
characteristic data strings from at least two of the number of RFID
tags.
2. The method of claim 1 wherein identifying the RFID tags includes
comparing at least a portion of each of the read characteristic
data strings to at least one of the characteristic data strings
stored in the buffer.
3. The method of claim 1, further comprising:
producing a human-perceptible indication corresponding to the
number of identified RFID tags.
4. The method of claim 1, further comprising:
producing a human-perceptible indication for each of the identified
RFID tags.
5. The method of claim 1, further comprising:
producing a human-perceptible indication having a characteristic
that varies corresponding to the number of identified RFID
tags.
6. The method of claim 1, further comprising:
producing a second human-perceptible indication each time one of
the read characteristic data strings matches at least one of the
characteristic data strings stored in the memory.
7. The method of claim 1, further comprising:
producing a second human-perceptible indication if all of the
characteristic data strings stored in the memory match at least a
respective one the read characteristic data strings.
8. The method of claim 1, further comprising:
relaying data from the identified RFID tags to a host computer.
9. The method of claim 1, further comprising:
transmitting an enable signal to a first one of the RFID tags that
has a respective characteristic data string that matches one of
characteristic data strings stored in the memory, the enable signal
comprising a command to activate a human-perceptible indicator on
the first one of the RFID tags.
Description
TECHNICAL FIELD
This application relates to methods and apparatus for reading data
carriers such as machine-readable symbols (e.g., barcode symbols,
area and/or matrix code symbols) and wireless memory devices (e.g.,
RFID tags).
BACKGROUND OF THE INVENTION
A variety of methods exist for tracking and providing information
about items. For example, inventory items typically carry printed
labels providing information such as serial numbers, price, weight,
and size. Some labels include data carriers in the form of
machine-readable symbols that can be selected from a variety of
machine-readable symbologies, such as bar code, and/or area or
matrix code symbologies. The amount of information that the symbols
can contain is limited by the space constraints of the label.
Updating the information in these machine-readable symbols
typically requires the printing of a new label to replace the old
label.
Data carriers such as memory devices provide an alternative method
for tracking and providing information about items. Memory devices
permit the linking of large amounts of data with an object or item.
Memory devices typically include a memory and logic in the form of
an integrated circuit ("IC") and means for transmitting data to
and/or from the device. For example, a radio frequency
identification ("RFID") tag typically includes a memory for storing
data, an antenna, an RF transmitter, and/or an RF receiver to
transmit data, and logic for controlling the various components of
the memory device. RFID tags are generally formed on a substrate
and can include, for example, analog RF circuits and digital logic
and memory circuits. The RFID tags can also include a number of
discrete components, such as capacitors, transistors, and
diodes.
RFID tags can be passive, active or hybrid devices. Active devices
are self-powered, by a battery for example. Passive devices do not
contain a discrete power source, but derive their energy from an RF
signal used to interrogate the RFID tag. Passive RFID tags usually
include an analog circuit that detects and decodes the
interrogating RF signal and that provides power from the RF field
to a digital circuit in the tag. The digital circuit generally
executes all of the data functions of the RFID tag, such as
retrieving stored data from memory and causing the analog circuit
to modulate the RF signal to transmit the retrieved data. In
addition to retrieving and transmitting data previously stored in
the memory, the RFID tag can permit new or additional information
to be stored in the RFID tag's memory, or can permit the RFID tag
to manipulate data or perform some additional functions. RFID tags
are available from a number of manufacturers, including Texas
Instruments, Dallas, Tex., and Omron of Japan.
Another form of memory device is an optical tag. Optical tags are
similar in many respects to RFID tags, but rely on an optical
signal to transmit data to and/or from the tag.
Additionally, touch memory data carriers are available, for example
touch memory devices from Dallas Semiconductor of Dallas, Tex.
Touch memory devices are similar to RFID tags but require physical
contact with to store and retrieve data.
A user typically secures a data carrier to an item, such as a good,
product, or container by way of a pressure sensitive adhesive. The
data carrier often encodes information specifically relating to the
item such as identifying or destination information. An individual,
such as a checkout or inventory clerk, can retrieve data about any
given item, for example, by scanning the machine-readable symbol or
interrogating the RF tag, optical tag, or touch memory device.
Access to the data can be useful at the point of sale, during
inventory, during transportation, or at other points in the
manufacture, distribution, sale, or use of the tagged item.
Relatively high cost is one of the drawbacks of memory devices,
thus, many applications rely on the less expensive printed
machine-readable symbols. Another significant drawback is the
difficulty of identifying a particular memory device from a group
of memory devices. It is particularly difficult to associate the
information read from the RFID tag with a physical item or
container. The ability to read data from different types of data
carriers, for example machine-readable symbols and RFID tags,
and/or to associate and manipulate such data can provide numerous
benefits in the automatic data collection ("ADC") industry.
SUMMARY OF THE INVENTION
In one aspect a data carrier reader includes an RFID tag reading
section and a machine-readable symbol reading section, which can
contain some common components. The reader is operable in an RFID
tag reading mode and/or a symbol reading mode. The reader provides
a consistent and intuitive user interface within, and between, the
operating modes. The user interface can include visual, aural and
tactile indicators. The visual indicators can include a pattern
displayed by indicators on the reader, or projected onto or near
the data carrier.
In another aspect, a data carrier reader is capable of executing a
number of different reading methods. A method for reading single
RFID tags can store read data to a buffer for eventual transmission
to a host, and can suppress redundant data. Another method
identifies all RFID tags having a characteristic data string that
appears on a list. In contrast, another method identifies any RFID
tags having a characteristic data string that does not appear on
the list. Still another method associates data read from an RFID
tag with a particular object or item using a data coded in a
machine-readable symbol. In a further method, the machine-readable
symbol is automatically read when the RFID tag is within a
predetermined proximity of the reader. In each method, a consistent
and intuitive output can be provided to the user to identify the
successful and unsuccessful operations such as reading an RFID tag
or machine-readable symbol.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, identical reference numbers identify similar
elements or acts. The sizes and relative positions of elements in
the drawings are not necessarily drawn to scale. For example,
various elements may be arbitrarily enlarged and positioned to
improve drawing legibility.
FIG. 1 is a partial block diagram, partial front elevational view
of a facility including a data carrier reader reading data carriers
carried by a number of items, the reader communicate with a host
through an interface.
FIG. 2 is a functional block diagram of the reader according to one
embodiment of the invention.
FIG. 3 is a top plan view of the reader of FIG. 2.
FIG. 4 is a partial top plan view of an alternative set of visual
indicators for the reader of FIG. 2.
FIGS. 5A-5C together form a chart of selected input and output
signals for operating the reader of FIG. 2 and the visual
indicators of FIG. 4.
FIG. 6 is a top plan view of a graphic display of the reader of
FIG. 3.
FIG. 7 is a top plan view of an alpha-numeric display of the reader
of FIG. 3.
FIG. 8 is a flowchart showing a method of reading single RFID
tags.
FIG. 9 is a flowchart showing a method of determining when a reader
is finished reading RFID tags.
FIG. 10 is a flowchart showing a method of reading multiple RFID
tags.
FIG. 11 is a flowchart showing a method of performing an inclusive
search of RFID tags.
FIG. 12 is a flowchart showing a method of performing an exclusive
search of RFID tags.
FIG. 13 is a flowchart showing a method of associating data from an
RFID tag with an item using a machine-readable symbol.
FIG. 14 is a flowchart showing a method of automatically imaging a
machine-readable symbol based on proximity to an RFID tag to
associate data from an RFID tag with an item using the
machine-readable symbol.
DETAILED DESCRIPTION OF THE INVENTION
In the following description, certain specific details are set
forth in order to provide a thorough understanding of various
embodiments of the invention. However, one skilled in the art will
understand that the invention may be practiced without these
details. In other instances, well-known structures associated with
RFID tags, RFID tag readers, one- and two-dimensional symbologies,
symbol readers, microprocessors and communication networks have not
been shown or described in detail to avoid unnecessarily obscuring
descriptions of the embodiments of the invention.
The headings provided herein are for convenience only and do not
interpret the scope or meaning of the claimed invention.
Data Carrier Reader
FIG. 1 shows a data carrier reader 10 reading one or more of a
number of data carriers, such as the RFID tags 12 on the containers
or items 14. The reader 10 includes a head 16, a handle 18 and a
trigger 20. An interface 22 can couple the reader 10 to a host 23,
such as a centralized computer, as described in detail below.
The tags 12 can take the form of an RFID tag 12A that carries a
machine-readable symbol 24A on a visible surface of the tag.
Alternatively, the tags 12 can take the form of a separate RFID tag
12B and machine-readable symbol 24B. The separate RFID tag 12B and
machine-readable symbol 24B can be physically associated, for
example, securing each to the same physical object, such as the
item 14. The RFID tag 12A, 12B and machine-readable symbol 24A, 24B
can contain logically associated information, for example
information related to the item 14 to which the tags 12 are
secured, such as identifying and/or shipping information.
As shown in FIG. 2, the reader 10 contains an RFID tag reading
section 30, a symbol reading section 32, a user input section 34, a
user output section 36, and a communications section 38 all coupled
by a bus 40. The bus 40 provides data, commands and/or power to the
various sections 30-38. The reader 10 can include an internal power
source such as a rechargeable battery (not shown) or can receive
power from an external power source such as a wall outlet by way of
an electrical cord (not shown). Each of these sections 30-38 will
be described individually below, although in the illustrated
embodiment some of these sections share common components.
RFID Tag Reading Section
FIG. 2 shows the RFID tag reading section 30 of the data carrier
reader 10 including an antenna 42 coupled to a radio 44. The radio
44 is coupled via the bus 40 to a microprocessor 46 and a random
access memory ("RAM") 48. The RAM 48 can include a characteristic
data string buffer 49 to temporarily store characteristic data
strings, as will be explained in detail below. Alternatively, the
reader 10 can include a discrete characteristic data string buffer
(not shown). While FIG. 2 shows a single microprocessor 46, the
data carrier reader 10 may include separate dedicated processors
for each of the RFID tag and symbol reading sections 30, 32.
While a dipole antenna 42 is shown, the data carrier reader 10 can
employ other antenna designs. Of course, the antenna can be
selected to achieve a particular focus, for example, a highly
directional antenna can enhance the ability of the reader 10 to
select a single RFID tag 12 out of a group of RFID tags. The radio
44 can take the form of a transceiver capable of transmitting and
receiving at one or more of the frequencies commonly associated
with RFID tags 12 (e.g., 350 kilohertz, 400 kilohertz, 900
kilohertz). While these frequencies typically fall within the radio
frequency range of the electromagnetic spectrum, the radio 44 can
successfully employ frequencies in other portions of the spectrum.
Antenna design and radios are generally discussed in The ARRL
Handbook for Radio Amateurs, 76.sup.th Ed., American Radio Relay
League, Newington, Conn., U.S.A. (1999) (ISBN: 0-87259-181-6), and
commonly assigned patent application U.S. Ser. No. 09/280,287,
filed Mar. 29, 1999, entitled ANTENNA STRUCTURES FOR WIRELESS
COMMUNICATIONS DEVICE, SUCH AS RFID TAG (Atty. Docket No.
480062.648).
A read only memory ("ROM") 50 stores instructions for execution by
the microprocessor 46 to operate the radio 44. As used in this
herein, ROM includes any non-volatile memory, including erasable
memories such as EEPROMs. The programmed microprocessor 46 can
control the radio 44 to emit an interrogation signal, including any
required polling codes or encryption, and to receive a return
signal from an RFID tag 12A, 12B. The programmed microprocessor 46,
RAM 48, radio 44 and antenna 42 thus form the RFID reading section
30.
Symbol Reading Section
FIG. 2 also shows the symbol reading section 32 of the data carrier
reader 10 including an image sensor 52 and an illumination source,
such as the laser 53. The image sensor 52 can take the form of a
one- or two-dimensional charge coupled device ("CCD") array.
Alternatively, the reader 10 can employ other known imaging
devices, for example laser scanners or Vidicons. In certain
embodiments, the data carrier reader 10 can omit the illumination
source, for example where the image sensor 52 is a two-dimensional
CCD array operable with ambient light. Alternatively, the data
carrier reader 10 can rely on other illumination sources, such as
light emitting diodes ("LEDs") or a strobe light, that can be
positioned to illuminate a desired one of the machine-readable
symbols 24A, 24B. The reader 10 can employ suitable optics such as
lens and mirrors (not shown) for directing light reflected from the
machine-readable symbol 24A, 24B to the image sensor 52.
The reader 10 includes an analog-to-digital ("A/D") converter 54,
to transform the analog electrical signals from the image sensor 52
into digital signals for use by the microprocessor 46. The bus 40
couples the image data from the A/D converter 54 to the
microprocessor 46 and the RAM 48. A portion of the RAM 48 can form
an image buffer 56 for temporarily storing data, such as a captured
image data from the image sensor 52. The ROM 50 contains
instructions for the microprocessor 46, that permit the
microprocessor 46 to control the image sensor 52 to capture image
data and to decode and/or manipulate the captured image data. The
programmed microprocessor 46, RAM 48, image sensor 52, and A/D
converter 54, thus form the symbol reading section 32.
Symbol reading and decoding technology is well-known in the art and
will not be discussed in further detail. Many alternatives for
image sensors, symbol decoders, and optical elements that can be
used in the reader 10 are taught in the book, The Bar Code Book,
Third Edition, by Roger C. Palmer, Helmers Publishing, Inc.,
Peterborough, N.H., U.S.A. (1995) (ISBN 0-911261-09-5).
Communications Section
The communications section 38 includes a communications buffer 47
and a communications port 49. The communications buffer 47 can
temporarily store incoming and outgoing data and/or commands where
the communications speed of the reader 10 does not match the
communications speed of some external device, such as the interface
22 (FIG. 1). The communications port 49 provides communications
between the reader and external devices. While shown as a hardwire
connection to the interface 22 (FIG. 1), the communications port
can be a wireless interface, and can even employ the antenna 42 and
radio 44 of the RFID tag reading section 30. Additionally, the
reader 10 can include the interface 22 as an integral part of the
reader 10.
The interface 22 (FIG. 1) can provide communications over a
communications network 68 to the host 23, allowing transmissions of
data and/or commands between the reader 10 and the host 23. The
communications network 68 can take the form of a wired network, for
example a local area network ("LAN") (e.g., Ethernet, Token Ring),
a wide area network ("WAN"), the Internet, or the World Wide Web
("WWW"). Alternatively or additionally, the communications network
68 can be a wireless network, for example, employing infrared
("IR"), satellite, and/or radio frequency ("RF")
communications.
The host 23 can receive from each of a number of the readers 10,
data collected from the RFID tags 12 and machine-readable symbols
24. The host 23 can use the data with a database, and can
automatically manipulate the data, for example to automatically
performing inventory or to track shipments.
The host 23 can provide data and commands to each of a number of
the readers 10. For example, the host can share data between the
readers 10, such as providing a list of either located or missing
identifiers, as will be discussed in more detail below in reference
to inclusive and exclusive searches. The host 23 can provide a
command to toggle the reader 10 between an RFID tag reading mode
and a symbol reading mode, which is described below in further
detail. Thus, the host 23 can command, coordinate and share data
between a number of readers 10. Commonly assigned patent
application U.S. patent application Ser. No. 09/401,066, filed Sep.
22, 1999, entitled, "SYSTEM AND METHOD FOR AUTOMATICALLY
CONTROLLING OR CONFIGURING A DEVICE, SUCH AS AN RFID READER" (Atty.
Docket No. 480062.672) contains teachings that can be used to
automatically control or configure the reader 10.
User Input Section
The user input section 34 includes the trigger 20, the mode switch
34, and can include a user input device 58. The bus 40 couples the
mode switch 34 to the microprocessor 46. In response to selection
of the mode switch 34, the microprocessor 46 switches between the
symbol reading mode and the RFID tag reading mode, for example by
toggling between the two operating modes. The reader 10 can employ
additional operating modes, or switching positions as desired, for
example a switch position that places the reader 10 in an OFF state
or a WAIT state to conserve energy.
In the symbol reading mode, the microprocessor 46 operates the
image sensor 52 to image one of the machine-readable symbols 24A,
24B. The microprocessor 46 decodes the imaged symbol to retrieve
the data encoded in the machine-readable symbol 24A, 24B, such as a
respective identifier. In the RFID tag reading mode, the
microprocessor 46 operates the radio 44 to emit an interrogation
signal and to receive a response from one or more of the RFID tags
12A, 12B to the interrogation signal. The microprocessor 46 decodes
the response signal to retrieve the data encoded in the RFID tag
12A, 12B, such as a respective identifier.
The mode switch 34 can be a membrane switch, mounted to the
exterior of the reader 10 for easy selection by the user. The mode
switch 34 can additionally, or alternatively, be implemented in the
software to supplement or replace the user selectable mode switch
on the exterior of the reader 10. The software implemented switch
is particularly useful where the host 23 (FIG. 1) controls the
operating mode of the reader 10. Alternatively, the mode switch 34
can be implemented as an icon on a touch sensitive display 74. In
further alternatives, the trigger 20 can function as the mode
switch 37. In one instance, the number of successive trigger pulls
or activations can determine the operating mode. For example, two
successive trigger pulls can select the symbol mode, while three
successive trigger pulls selects the RFID mode; or a single trigger
pull can cause the reader 10 to read a symbol while a double
trigger pull toggles between the symbol and RFID modes.
Alternatively, the duration of trigger activation can determine the
operating mode. For example, a trigger pull of under 0.5 seconds
can select the symbol mode, while a trigger pull of longer than 0.5
seconds can select the RFID mode; or a trigger pull of under 0.5
seconds can cause the reader 10 to read a symbol while a trigger
pull of over 0.5 seconds toggles the reader between the symbol and
RFID modes. Additionally, or alternatively, the mode switch can be
context sensitive, switching modes based on data read from a
previously read data carrier 12A, 12B, 24A, 24B. For example, a
previously read RFID tag 12A can indicate the existence of a symbol
24A. In response, the data carrier reader 10 can automatically
switch into symbol mode and read the symbol 24A associated with the
RFID tag 12A.
The bus 40 also couples the trigger 20 to the microprocessor 46. In
response to activation of the trigger 20, the microprocessor 46 can
cause the image sensor 52 to image one of the machine-readable
symbols 24A, 24B when the reader 10 is operating in the symbol
reading mode. In at least one embodiment, the microprocessor 46 can
also cause the radio 44 and antenna 42 to emit an interrogation
signal in response to the activation of the trigger 20 while in the
reader 10 is operating in the RFID tag reading mode.
The user input device 58 can take the form of a keypad 60 (FIG. 3),
mouse, touch screen and/or other user operable device to input
information and/or commands to the reader 10. The bus 40 couples
the user input device 58 to the microprocessor 46, to allow the
user to enter data and commands.
User Output Section
The user output section 36 includes human-perceptible visual and
audio indicators 62, 64 respectively. The bus 40 couples the visual
and audio indicators 62, 64 to the microprocessor 46 for control
thereby. The visual indicators 62 can take a variety of forms, for
example: light emitting diodes ("LEDs"); a graphic display such as
a liquid crystal display ("LCD"), and/or an alpha-numeric display
such as a 7-segment display. The audio indicator 64 can take the
form of one or more dynamic, electrostatic or piezo-electric
speakers 66. The speaker 66 is operable to produce a variety of
sounds (e.g., Clicks and Beeps), and/or frequencies (e.g., tones),
and to operate at different volumes. The reader 10 can also include
tactile indicators such as a vibrating member. The specific
operation of the user output section 36 is discussed in more detail
below.
FIG. 3 shows a portion of the user interface located on the head 16
of the reader 10. The user interface includes the elements of the
user input section 34, such as the trigger 20, the mode switch 34
and the keypad 60. The user interface also includes the elements of
the user output section 36 including the visual indicators 63 and
the speaker 66. In particular, the visual indicators 62 in the
illustrated embodiment include a set of RFID related LEDs 70, a set
of machine-readable symbol related LEDs 72, and a display 74.
The data carrier reader 10 can additionally, or alternatively,
employ the laser 53 as the visual indicator. The laser can be
successively pulsed or flashed according to a set of predefined
human-recognizable temporal patterns to provide information to the
user, such as user indications corresponding to the various reader
operations and/or the responses from the date carriers 12A, 12B,
24A, 24B. Employing the laser 53 as a portion of the user interface
provides a number of distinct benefits. For example, operating the
laser 53 to provide human-recognizable patterns can eliminate the
need for other visual indicators 62. The data carrier reader 10 can
employ multiple illumination sources such as lasers 53 or LEDs of
different colors, or an illumination source capable of producing a
number of different colors to provide the appropriate user
indications, as set out in FIGS. 5A-5C. As discussed in detail
below, the human-recognizable patterns can take the form of a
predefined sequence of laser flashes of one or more colors,
separated by time (i.e., temporal pattern).
The visual and audio indicators 62, 64 are configured to provide an
intuitive user interface consistent across the RFID tag and symbol
reading modes. For example, the RFID tag related and symbol related
LED sets 70, 72 each contain green 76, 78, yellow 80, 82 and red
84, 86 LEDs, in an order or pattern that is consistent between the
sets. The particular LED 76-86, as well as the number and/or
pattern of flashes, is set such that the same color LEDs flash the
same pattern for analogous RF tag reading and symbol reading
activities. For example, the yellow LED 80 in the RFID tag related
set 70 flashes during the reading of one of the RFID tags 12A, 12B
(FIG. 1), while the yellow LED 82 in the machine-readable symbol
related set 72 flashes during the reading of one of the
machine-readable symbols 24A, 24B (FIG. 1). The reader 10 responds
to a successful read of the RFID tag 12A, 12B or machine-readable
symbol 24A, 24B by illuminating the corresponding green LED 76, 78,
respectively, for a set period of time such as 5 seconds. The red
LEDs 84, 86 can indicate unsuccessful or incomplete operations. The
user receives visual feedback, where the color, position and
sequence of the visual indicators 62 is consistent within, and
across the RFID tag and symbol operating modes. Consistent feedback
can reduce training time and costs, and can lead to more efficient
operation of the reader 10.
Similar to the visual indicators 62, the speaker 66 provides
consistent feedback within and across the operating modes. In the
illustrated embodiment, the speaker 66 emits a "beep" or a "click"
sound, although the speaker 66 can emit different and/or additional
sounds. The speaker 66 can emit, for example, a single beep each
time either an RFID tag 12A, 12B or a machine-readable symbol 24A,
24B is successfully read. When searching a field of RFID tags 12A,
12B for one or more particular tags, the speaker 66 can emit a
click for each non-match and a beep for each match.
The user interface can also include an ON/OFF indicator 97, and/or
a Low Power indicator 99 to identify the operating condition of the
reader 10.
FIG. 4 shows an alternative set of visual indicators for the reader
10. his alternative embodiment, and those alternative embodiments
and other alternatives described herein, are substantially similar
to previously described embodiments, and common acts and structures
are identified by the same reference numbers. Only significant
differences in operation and structure are described in detail
below.
The reader 10 of FIG. 4 employs only three LEDs to simplify
switching while providing the human-perceptible visual indications.
A two state LED serves as the machine-readable symbol related
indicator 87. The machine-readable symbol indicator 87 produces no
light in an OFF state and a Green light in an ON state. A three
state LED serves as the RFID related indicator 89. The RFID related
indicator 89 produces a Green light in first ON state, a Yellow
light in second ON state, and NO light in an OFF state. A two state
LED serves as the ON/OFF indicator 97. The ON/OFF indicator
produces a Yellow light, or No light. The ON/OFF indicator is
proximate the machine-readable symbol related and RFID related
indicators 87, 89. In FIG. 4, the mode switch 34 takes the form of
a toggle or slider switch, having a neutral position (center), a
symbol mode position (left of center) and an RFID mode position
(right of center). The positions are consistent with the
corresponding visual indicators 87, 89, respectively.
FIGS. 5A-C describe a variety of input and outputs signals for the
reader 10, and particularly for the audio indicator 64 and laser 53
of FIG. 2, and for the visual indicators 87, 89, 97 of FIG. 4.
While the table is self-explanatory, a brief description of the
columns follows. Column 31 defines a reader status or error
conditions corresponding to reader activities. Column 33 describes
the operation of the visual indicators 87, 89, 97 of FIG. 4, in
response to the various reader status or errors conditions.
Similarly, column 35 describes the operation of the audio indicator
64 in response to the various reader status or error conditions 33.
Column 37 describes the operation of the laser to produce the
desired human-recognizable patterns corresponding to the various
reader status or errors conditions 31. Column 39 describes messages
for display on the display 74 corresponding to the various reader
status or errors conditions 31. Column 41 describes PDT/Host
messages corresponding to the various reader status or errors
conditions 31. Column 43 describes data and/or error codes sent to
the host 33, corresponding the various reader status or errors
conditions 31. As discussed above, these user indications provide a
consistent interface for the user within and across the operating
modes, permitting the user to efficiently operate the reader
10.
The display 74 can additionally, or alternatively, provide the user
other visual indications. For example, a graphical display 88 (FIG.
6), can employ a first set of icons 90 to indicate RFID tag
activities and a second set of icons 92 to indicate symbol reading
activities. (Note, typically only a single icon will be displayed
at a time, although multiple icons are shown in FIG. 6 for the
convenience of this description.) For example, screen icons 81, 83
and 85 can represent RFID reading, successful reading of the RFID
tag 12A, 12B, and unsuccessful reading of RFID tag 12A, 12B,
respectively. Similarly, screen icons 91, 93 and 95 can represent
machine-readable symbol reading, successful reading of the
machine-readable symbol 24A, 24B, and unsuccessful reading of the
machine-readable symbol 24A, 24B, respectively.
Similarly, an alpha-numeric display 94 (FIG. 7) can employ a first
set of words 96 to indicate RFID tag activities and a second set of
words 98 to indicate symbol reading activities. (Again, typically
only a single word will be displayed at a time, although multiple
are shown in FIG. 7 for the convenience of this description.) The
display 94 is self-explanatory and in the interest of brevity will
not be further described. Other visual indications, as well as
audio and tactile indications are of course possible.
Selected Methods of Operation
Different methods of operating the reader 10 or a reader having
similar capabilities are disclosed below. As set out in the below
methods, the intuitive and consistent operation of the user
interface within and across operating modes can provide numerous
benefits. While several methods are set out for illustration, other
methods employing similar techniques are within the scope of the
invention. Also, the following descriptions employ certain
descriptions of user outputs (e.g., Beep, Click, Red LED, Yellow
LED, and Green LED) for convenience of description. Those skilled
in the art will appreciate that other sounds, colors, visual,
tactile indications, and/or other human-perceptible indications
could be used.
Single Tag Read Mode
FIG. 8 shows a method 100 of reading RFID tags 12A-12B (FIG. 1)
employing the reader 10 (FIGS. 1-3). Turning on the reader 10, or
switching into the RFID tag reading mode, can automatically cause
the microprocessor 46 to start the method 100 in step 102.
Alternatively, or additionally, the user can cause the
microprocessor 46 to start the RFID tag reading method 100 by
selecting an appropriate key from the keypad 60 or icon from the
display 74. Upon starting in step 102, the microprocessor 46 can
perform an initialization process, for example loading appropriate
operating instructions from the ROM 50 to the RAM 48, initializing
the characteristic data string buffer 49 and/or performing a series
of systems checks on the various component and subsystems of the
reader 10, as set out in step 104.
Under the instructions loaded in the RAM 48, the microprocessor 46
activates the radio 44 in step 106. In step 108, the radio 44
receives data from the RFID tags 12A, 12B. The radio 44 can emit an
interrogation signal to cause the RFID tags 12A, 12B to respond,
or, the radio 44 can simply receive signals from RFID tags 12A, 12B
that emit signals without interrogating the RFID tags. A variety of
passive, active and hybrid RFID tags 12A, 12B are known in the art
and will not be discussed in further detail. A discussion of RFID
tags can be found in commonly assigned patent applications: U.S.
Ser. No. 09/173,539, filed Oct. 15, 1998, entitled WIRELESS MEMORY
DEVICE AND METHOD OF MANUFACTURE (Atty. Docket No. 480062.630);
U.S. Ser. No. 09/164,203, filed Sept. 30, 1998, entitled MEMORY TAG
AND METHOD OF MANUFACTURE (Atty. Docket No. 480062.632); U.S. Ser.
No. 09/173,137, filed Oct. 15, 1998, entitled RF TAG HAVING STRAIN
RELIEVED STIFF SUBSTRATE AND HYDROSTATIC PROTECTION FOR A CHIP
MOUNTED THERETO (Atty. Docket No. 480062.635); and U.S. Ser. No.
09/164,200, filed Sept. 30, 1998, entitled CHIP PLACEMENT ON SMART
LABELS (Atty. Docket No. 480062.642).
In step 110, the microprocessor 46 determines whether duplicate tag
data should be suppressed. If suppressed, previously read or
acquired data will not be stored or reported a second time.
Suppression can be a user selection, or can be a selection
transferred from the host 23, or can be preset, for example by the
reader manufacturer or owner. If suppression is not active, the
reader 10, in step 112, automatically transmits the read data, for
example to the host 23, and provides an indication to the user that
the data has been received and transmitted. To provide the
indication, the reader 10 activates the speaker 66 to emit a single
"beep" and activates the Green RFID related LED 76 for a short
time, in steps 114, 116, respectively. Control passes to an end of
the routine 100, in step 118.
If suppression is active, the microprocessor 46, compares a
characteristic data string from the received data to other
characteristic data strings stored in the characteristic data
string buffer 49, in step 120. The characteristic data string can
be any string of characters stored in the RFID tags 12A, 12B that
permit the reader 10 to determine whether a particular RFID tag
12A, 12B has been read more than once. For example, the
characteristic data string can be a unique identifier programmed
into each of the RFID tags 12A, 12B. Alternatively, the
characteristic data string can be the entire set of data stored in
the RFID tag 12A, 12B, or can be any subset or field of data
recognizable by position, offset, delimiter or other such field
identifier. The microprocessor 46 branches at step 122 based on the
determination of whether the received characteristic data string
corresponds, or matches, any of the stored data strings.
If the received characteristic data string corresponds to, or
matches, any of the stored characteristic data strings, the reader
10 provides an indication that the RFID tag 12A, 12B has been read
again, activating the speaker 66 to emit a single "click" and
activating or "flashing" the Red RFID related LED 84 in steps 124,
126, respectively. The microprocessor 46 determines in step 128, if
the reader 10 is finished reading RFID tags 12A, 12B, as described
in detail below.
If the received characteristic data string does not correspond to,
or match any of the stored data strings, the microprocessor 46
updates the characteristic data string buffer 49 containing the
read characteristic data strings, for example storing the newly
received characteristic data string to the buffer 49 in step 130.
The reader 10 can automatically transmit the read data in step 132,
for example to the host 23 (FIG. 1). The reader 10 also provides an
indication that a new RFID tag 12A, 12B has been read (e.g., read
for the first time since the buffer 49 was initialized), activating
the speaker 66 to emit a "beep" in step 134 and activating the
Green RFID related LED 76 in step 136. Control passes to the end of
the routine 100 in step 118.
FIG. 9 is a flowchart of a method 200 of determining when a reader
10 is finished reading. The microprocessor 46 can execute this
method 200 in place of each step labeled "DONE" in the various
other methods, such as at step 128 of FIG. 8 (discussed above), or
in the other Figures (discussed below). As set out in the Figures,
the method 200, starting at step 202, acts as a function or
subroutine, returning a Boolean value (e.g., TRUE/FALSE, YES/NO, or
DONE/NOT DONE conditions). While the method 200 could be
implemented as an integral part of the other methods discussed
herein, it is set out separately for ease of discussion.
At step 240, the microprocessor 46 determines whether the trigger
20 has been released. A trigger release indicates that the user is
finished reading. If the trigger 20 has been released, the
microprocessor 46 sets the Boolean value to "DONE" at step 242, and
passes control to an end of the routine 200 at step 218, returning
the appropriate Boolean value. For example, when returning to the
method 100 (FIG. 8), the condition "DONE" can cause the reader 10
to stop interrogating RFID tags 12A, 12B.
If the trigger 20 has not been released, the microprocessor 46 in
step 244 determines whether a timeout condition has been exceeded.
For example, the reader 10 can assume that all RFID tags 12A, 12B
have been read if a new (e.g., not previously read) tag is not
found after some length of time or some number of consecutive
repeatedly read RFID tags 12A, 12B. While the length of time or
number of repeated reads can be preset, the length or number of
repeats can also be determined during the reading, for example as a
function of RFID tag density (e.g. number of RFID tags per unit
time). The microprocessor 46 can rely on an internal clock or a
separate clock circuit (not shown) in measuring the timeout period.
Employing RFID tag density to calculate the stopping condition "on
the fly" reduces the likelihood of ending a search prematurely
.
If the timeout condition is exceeded, the reader 10 considers
reading to be finished, sets the Boolean value to "DONE" at step
242, and passes control to the end of the method 200 at step 218,
producing the appropriate Boolean value for determining the next
operation, such as turning the radio OFF. If the timeout condition
is not exceeded, the microprocessor 46 determines whether a stop
command has been received from the host 23 in step 246. If a stop
command has been received, the Boolean value is again set to "DONE"
at step 242, and control passes to the end of the method 200 at
step 218. If a stop command has not been received from the host 23,
the microprocessor 46 at step 248, determines whether all RFID tags
12A, 12B have been read. If all RFID tags 12A, 12B have been read,
the Boolean value is set to "DONE" at step 242 and control passes
to the end of the method 200 at step 218, returning the appropriate
response. If all RFID tags 12A, 12B have not been read, the Boolean
value is set to "NOT DONE" at step 250 and control passes to the
end 218, thereby returning the appropriate Boolean value.
Multi Tag Read/Write Modes
FIG. 10, shows an additional, or alternative embodiment of
operating under the present invention. Similar steps in the methods
are assigned reference numerals that have the two least significant
digits in common (e.g., the "Start" step is respectively numbered:
102, 202, 302, . . . , 702 in FIGS. 6-12, respectively).
FIG. 10 shows a method 300 of reading multiple RFID tags 12A, 12B
(FIG. 1) employing the reader 10 (FIGS. 1-3). In a similar fashion
to the method 100, the microprocessor 46 starts executing the
method 300 at step 302, initializing the reader 10 at step 304,
turning ON the radio 44 in step 306, and receiving responses from
the RFID tags 12A, 12B in step 308. In step 320, the microprocessor
46 compares a characteristic data string from the received data to
other characteristic data strings stored in the characteristic data
string buffer 49 to determine whether the reader 10 has read the
particular RFID tag 12A, 12B before. The microprocessor 46 branches
at step 322 based on the determination of whether the received
characteristic data string corresponds, or matches, any of the
stored data strings.
If the received characteristic data string corresponds to, or
matches, any of the stored characteristic data strings, the
microprocessor 46 adds the read characteristic data string to the
characteristic data string buffer 49, at step 330. The reader 10
provides an indication that the read RFID tag 12A, 12B has been
previously read, activating the speaker 66 to emit a single "click"
and activating or "flashing" the Red RFID related LED 84 at steps
352 and 354, respectively. In step 356, the microprocessor 46
examines a counter ("Retry") to determine whether a maximum number
of iterations has been exceeded without finding a "new" (e.g. not
previously read) RFID tag 12A, 12B. If the number of iterations
without encountering a new RFID tag 12A, 12B has been exceeded,
control passes to an end of the method 300 at step 318. If the
number of iterations without encounter a new RFID tag 12A, 12B has
not been exceeded, the microprocessor 46 increments the Retry
counter in step 358, and determines in step 328 whether the reader
10 is finished reading RFID tags 12A, 12B, as described in detail
above with respect to method 200 (FIG. 9). The microprocessor 46
returns to receiving RFID tag responses in step 308, or passes
control to the end of the method 300 at step 318 based on the
Boolean value returned by the method 200 (FIG. 9).
If the received characteristic data string does not correspond to,
or match any of the stored data strings, the microprocessor 46
resets the Retry counter in step 360, and adds the read
characteristic data string to the characteristic data string buffer
49 in step 362. The reader 10 in step 364, automatically transmits
the read data, for example to the host 23. The reader 10 also
provides an indication that a new RFID tag 12A, 12B has been read
(e.g., read for the first time since the buffer 49 was
initialized), activating the speaker 66 to emit a "beep" in step
314 and activating the Green RFID related LED 76 in step 316. The
microprocessor 46 determines in step 328 whether the reader 10 is
finished reading RFID tags 12A, 12B, as described in detail above
with respect to method 200 (FIG. 9). The microprocessor 46 returns
to receiving RFID tag responses in step 308 or passes control to
the end of the method 300 in step 318 based on the condition
returned by the method 200.
Inclusive Search
The reader 10 can perform an "inclusive" search, such as finding
all RFID tags 12A, 12B on a list of RFID tags 12A, 12B. FIG. 11
shows a method 400 for performing an inclusive search. The user can
start the inclusive search 400 by, for example, selecting an
appropriate key or icon as in step 402. The microprocessor 46
performs an initialization at step 404, for example loading a list
of characteristic data strings for the RFID tags 12A, 12B to be
located or identified into the characteristic data string buffer
49. The list of characteristic data strings can, for example, be
downloaded from the host 23 via interface 22. The microprocessor 46
turns ON the radio 44 at step 406.
In step 408, the radio 44 interrogates the RFID tags 12A, 12B to
receive response signals containing the respective characteristic
data strings. Alternatively, the radio 44 can receive the response
signals without interrogating if the RFID tags 12A, 12B are active
and periodically transmit data without requiring initiation by an
interrogation signal. In step 420, the microprocessor 46 compares
the received characteristic data string with the characteristic
data strings stored in the characteristic data string buffer 49.
The microprocessor 46 branches at step 422, based on the
determination of whether the received characteristic data string
corresponds, or matches, any of the stored data strings.
If the read characteristic data string corresponds to, or matches
any of the stored characteristic data strings, then one of the RFID
tags 12A, 12B has been found and the reader 10 reports such to the
user and/or host 23. The reader 10 provides the user indication by
activating the speaker 66 to "beep" in step 414 and activating or
"flashing" the Green RFID related LED 76 in step 416. If the read
characteristic data string does not correspond to, or match any of
the stored characteristic data strings, then one of the RFID tags
12A, 12B has not been found, and the reader 10 reports such to the
user, and/or host 23. The reader 10 provides the user indication by
activating the speaker 66 to "click" in step 424 and activating or
"flashing" the Red RFID related LED 84 in step 426.
After providing the user indications, the microprocessor determines
whether the reader is finished reading, in step 428. If the reading
is finished, the returned Boolean value (i.e., DONE) causes control
to pass to an end of the inclusive search routine 400 in step 418.
If the reading is not finished, the returned Boolean value (i.e.,
NOT DONE) causes the radio 22 to continue receiving response
signals, passing control to step 418.
Exclusive Search
The reader 10 can perform an "exclusive" search, such as finding
any RFID tags 12A, 12B not on a list of RFID tags 12A, 12B. FIG. 12
shows a method 500 for performing an exclusive search. The user can
start the exclusive search 500 at step 502 by, for example,
selecting an appropriate key or icon. The microprocessor 46
performs an initialization at step 504, for example loading a list
of characteristic data strings for the RFID tags 12A, 12B to be
located. At step 506, the microprocessor turns ON the radio 44.
In step 508, the radio interrogates the RFID tags 12A, 12B to
receive response signals containing the respective characteristic
data strings. Alternatively, the radio can receive the response
signals without interrogating if the RFID tags 12A, 12B are active
and periodically transmit without requiring an interrogation
signal. In step 520, the microprocessor 46 compares the received
characteristic data string with the characteristic data strings
stored in the characteristic data string buffer 49. The
microprocessor 46 branches at step 566, based on the determination
of whether the received characteristic data string does not
correspond, or match, any of the stored data strings.
If the read characteristic data string does not correspond to, or
match any of the stored characteristic data strings, then one of
the RFID tags 12A, 12B missing from the list has been found, and
the reader 10 reports such to the user and/or host 23. The reader
10 provides the user indication by activating the speaker 66 to
"beep" in step 514, and activating or "flashing" the Green RFID
related LED 76 in step 516. If the read characteristic data string
corresponds to, or matches any of the stored characteristic data
strings, then one of the RFID tags 12A, 12B missing from the list
has not been found, and the reader 10 reports such to the user,
and/or host 23. The reader 10 provides the user indication by
activating the speaker 66 to "click" in step 524, and activating or
"flashing" the Red RFID related LED 84 in step 526.
After providing the user indications, the microprocessor 46
determines whether the reader 10 is finished reading, in step 528.
If the reading is finished, the returned Boolean value (i.e., DONE)
causes control to pass to an end of the exclusive search routine
500 in step 518. If the reading is not finished, the returned
Boolean value (i.e., NOT DONE) causes the radio to continue
receiving response signals, passing control to step 508.
Association of RFID Tag Data With Item Using Machine-Readable
Symbol
Often a user desires to make a physical association between the
data read from one of the RFID tags 12A, 12B and a particular
object or item 14 (FIG. 1). While the RFID tag 12A, 12B may be
attached to, or contained with the item, it can be difficult to
identify the particular RFID tag 12A, 12B that is being read. For
example, trying to identify one or more bags in a cargo hold, or
cargo container on an airliner is difficult and time consuming
using only RFID tags 12A, 12B. Each bag would have to be isolated
and the RFID tag 12A, 12B read to ensure that the read data came
from the RFID tag 12A, 12B associated with the particular bag. At
least one proposed solution involves placing human-perceptible
indicators on each of the RFID tags, as disclosed in the commonly
assigned U.S. patent application Ser. No. 09/249,359, filed Feb.
12, 1999, entitled, "METHOD AND APPARATUS FOR HUMAN-PERCEPTIBLE
IDENTIFICATION OF MEMORY DEVICES, SUCH AS RFID TAGS" (Atty. Docket
No. 480062.663). This solution can be relatively expensive since
each RFID tag 12A, 12B requires its own human-perceptible indicator
which complicates RFID tag manufacture.
FIG. 13 shows a method 600 of associating the read data from the
RFID tag 12A, 12B with a particular one of the items 14. The
association method 600 assumes that an RFID tag 12A, 12B has
already been read, a characteristic data string retrieved and
stored, for example, in the characteristic data string, buffer 49.
The user can start the association method 600 in step 602, as
discussed generally above. Alternatively, the reader 10 can be
configured to automatically start the association method 600 at
step 602. In step 668, the microprocessor 46 enters the symbol
reading, mode. The user activates the trigger 20 in step 670,
causing the microprocessor 46 to activate the image sensor 52 to
read the machine-readable symbol 24A, 24B at which the reader 10 is
directed. In step 672, the image sensor 52 acquires data from the
machine-readable symbol 24A, 24B by scanning, digitizing, or by any
commonly known methods in the relevant art. As part of acquiring
the data, the microprocessor 46, or a dedicated processor (not
shown), decodes the image to acquire a characteristic data stringy
encoded in the machine-readable symbol 24A, 24B. Methods and
apparatus for acquiring data from machine-readable symbols are
commonly known in the art, and are specifically taught in The Bar
Code Handbook 3.sup.rd ED., by Palmer, Roger C, Helmers Publishing,
Inc. (ISBN 0-911261-09-5), and, in the interest of brevity, will
not be described in further detail.
To determine whether the machine-readable symbol 24A, 24B that the
reader 10 is pointing at is associated with the RFID tag data read
by the reader 10, the microprocessor 46 compares a characteristic
data string read from the RFID tag, 12A, 12B with the
characteristic data string read from the machine-readable symbol
24A, 24B, in step 620. The user can visually associate the RFID tag
12A, 12B with the machine-readable symbol 24A, 24B since the RFID
tag 12A includes the machine-readable symbol 24A, or the RFID tag
12B and machine-readable symbol 24B are carried by the same item
14, or can be visually associated is some other manner. The user
can therefore determine that the data is from a particular RFID tag
12A, 12B when a match is indicated by the reader 10.
If the characteristic data string from the machine-readable symbol
24A, 24B corresponds to, or matches, the characteristic data string
from the RFID tag 12A,12B, the reader 10 provides an indication
that an association exists. To provide the indication, the
microprocessor 46 activates the speaker 66 to emit a single "beep"
in step 614 and activates or "flashes" the Green RFID related LED
76 and the Green symbol related LED 78 in step 674. The RFID
related and the symbol related LEDs 76, 78 are each activated,
indicating that both an RFID tag 12A, 12B and a machine-readable
symbol 24A, 24B have been located, providing a consistency across
the user interface.
In step 676, the microprocessor 46 can turn OFF the image sensor 52
after having found an association. In step 612, the reader 10 can
report the data, for example transmitting the RFID data to the host
23 via the communications port 38 and interface 22. In step 676,
the reader 10 can receive a direction or command from the host 23
via the interface 22 and the communications port 38. In step 678,
the microprocessor 46 determines whether the buffer should be
modified based on the command from the host 23. If the buffer is to
be modified, the microprocessor 46 modifies the buffer at step 680,
and passes control to an end of the association method 600 in step
618. Otherwise, the microprocessor 46 passes control directly to
the end of the association method, in step 600, without modifying
the buffer.
If the characteristic data string from the machine-readable symbol
24A, 24B does not correspond to, or match the characteristic data
string from the RFID tag 12A,12B, the reader 10 provides an
indication that an association does not exist. To provide the
indication, the microprocessor 46 activates the speaker 66 to emit
a three "Beeps" in step 682, and activates or "flashes" the Red
RFID related LED 84 and the Green symbol related LED 78 in steps
626, 684, respectively. The Green symbol related LED 78 is flashed
to indicate that a symbol has been successfully read, while the Red
RFID related 84 is flashed to indicate that the data is not
associated with the machine-readable symbol 24A, 24B, further
providing consistency across the user interface. The microprocessor
46 proceeds to the end of the method 600, in step 618.
Automatically Reading A Symbol Based On Proximity To RFID Tag, or
Frequency of RFID Tag's Responses
FIG. 14 shows a method 700, in which the reader 10 automatically
reads the machine-readable symbol when the reader 10 is within a
defined proximity of the RFID tag 12A, and hence within the defined
proximity of the machine-readable symbol 24A. The automated symbol
reading feature provides numerous benefits, for example the
automated symbol reading feature can simplify operation of the
reader, and/or reduce the probability of user error. The automated
symbol reading feature can also reduce the amount of labor required
to operate the reader 10, and can even eliminate the need for a
human operator. The method 700 of FIG. 14 can be used as part of,
or with, many of the previously described methods.
The antenna 42 in the reader 10 can be directionally sensitive. The
directionally sensitive antenna 42 has a directional range, in
other words, the antenna is more sensitive in certain directions
than other directions. As the reader 10 approaches a particular
RFID tag 12A, 12B, that RFID tag 12A, 12B spends a higher
percentage of time within the range of the reader 10. In contrast,
other RFID tags 12A, 12B are in the range a lower percentage of
time. Thus, as the reader 10 comes within a predefined proximity of
the RFID tag 12A, 12B, the number of "hits" (i.e., reading an RFID
tag having a desired characteristic data string) will increase, and
the number of "misses" (i.e., reading RFID tags not having the
desired characteristic data string) will decrease. The user may
recognize this from an increase in the number of "Beeps" and a
decrease in the number of "Clicks" emitted by the reader 10. The
microprocessor 46 in the reader 10, can keep track of the number of
hits and the number of misses for some unit length of time, steps
786, 788, respectively. The microprocessor 46 can determine a ratio
of the number of hits per unit of time and the number of misses per
unit of time. Alternatively, the host 23 can process the same
information.
In step 790, the microprocessor 46 determines whether the ratio of
hits to misses exceeds a symbol reading threshold. If the ratio
does not exceed the symbol reading threshold, the microprocessor 46
returns to step 786 and the reader 10 continues to read the RFID
tags 12A, 12B, continually revising and checking the ratio against
the threshold.
If the ratio exceeds the symbol reading threshold, the
microprocessor 46 turns the image sensor 52 ON, for example,
switching from the RFID reading mode to the symbol reading mode in
step 768. The microprocessor 46 controls the image sensor 52 to
image and decode the machine-readable symbol 24A, 24B in 772. In
step 774, the microprocessor 46 turns the image sensor 52 OFF,
thereby conserving power. In step 720, the microprocessor 46
compares the characteristic data string from the machine-readable
symbol 24A, 24B to the characteristic data string from the RFID tag
12A, 12B.
If the characteristic data string from the machine-readable symbol
24A, 24B corresponds to, or matches, the characteristic data string
from the RFID tag 12A, 12B, the reader 10 provides an indication
that an association exists. To provide the indication, the
microprocessor 46 activates the speaker 66 to emit a single "Beep"
in step 714 and activates or "flashes" the Green RFID related LED
76 and the Green symbol related LED 78 in step 774. The RFID
related and the symbol related LEDs 76, 78 are each activated,
indicating that both an RFID tag 12A, 12B and a machine-readable
symbol 24A, 24B have been located, providing a consistency across
the user interface.
In 712, the reader 10 can report the data, for example
automatically transmitting the RFID data to the host 23 via the
communications port 38 and interface 22. In step 776, the reader 10
can receive a direction or command from the host 23 via the
interface 22 and the communications port 38. In step 778, the
microprocessor 46 determines whether the characteristic data string
buffer 49 should be modified based on the command from the host 23.
If the buffer 49 is to be modified, the microprocessor 46 modifies
the buffer at step 780, and passes control to an end of the
association method 700 at step 718. Otherwise, the microprocessor
46 passes control directly to the end of the association method 700
at step 718 without modifying the characteristic data string buffer
49.
If the characteristic data string from the machine-readable symbol
24A, 24B does not correspond to, or match the characteristic data
string from the RFID tag 12A,12B, the reader 10 provides an
indication that the association does not exist. The microprocessor
46 activates the speaker 66 to emit three "Beeps" in step 782, and
activates or "flashes" the Green symbol related LED 78 and the Red
RFID related LED 84 in steps 784 and 726, respectively. The Green
symbol related LED 78 is flashed to indicate that a symbol has been
successfully read, while the Red RFID related 84 is flashed to
indicate that the data is not associated with the machine-readable
symbol 24A, 24B, further providing consistency across the user
interface.
SUMMARY
The various embodiments described above can be combined to provide
further embodiments. All of the above U.S. patents, patent
applications and publications referred to in this specification are
incorporated by reference. Aspects of the invention can be
modified, if necessary, to employ systems, circuits and concepts of
the various patents, applications and publications to provide yet
further embodiments of the invention.
Although specific embodiments of and examples data carrier readers
and reading are described herein for illustrative purposes, various
equivalent modifications can be made without departing from the
spirit and scope of the invention, as will be recognized by those
skilled in the relevant art. The teachings provided herein of the
invention can be applied to any data carrier reader, not
necessarily the exemplary combination RFID tag and symbol reader
generally described above.
For example, some of the structures and methods can be used with
readers capable of reading only RFID tags. Some of the structures
and methods can be used with readers capable of reading only
machine-readable symbols. Some of the structures and methods can be
suitable with readers for other data carriers, such as optical tags
and touch memory devices. The methods and structures are generally
applicable with other wireless memory devices, not just radio
frequency, and the term RFID as used herein is meant encompass
wireless memory devices operating in all ranges of the
electromagnetic spectrum, not only the radio frequency portion.
Similarly, the structures and methods disclosed can work with any
variety of modulation techniques, including, but not limited to,
amplitude modulation, frequency modulation, phase modulation and/or
pulse width modulation. The structures and methods can also be
applied to various machine-readable symbologies, including, but not
limited to, bar codes, stacked codes, area and/or matrix codes. The
image sensor 52 can be any type of image capture device, including
laser scanners, one- and two-dimensional charged coupled devices,
Vidicons, and the like.
These and other changes can be made to the invention in light of
the above-detailed description. In general, in the following
claims, the terms used should not be construed to limit the
invention to the specific embodiments disclosed in the
specification and the claims, but should be construed to include
all apparatus and methods that operate in accordance with the
claims. Accordingly, the invention is not limited by the
disclosure, but instead its scope is to be determined entirely by
the following claims.
* * * * *